Valve rocker arm and pivot assembly

ABSTRACT

A valve rocker arm and pivot assembly for use in the overhead valve gear of an internal combustion engine in which the valve rocker arm has a convex upper intermediate bearing portion fulcrumed against a concave bearing channel in the domed roof of a rocker arm cover fixed to the cylinder head of the engine. The bearing portion of the rocker arm is provided with an oil groove connected through a passage in the rocker arm to receive lubricating fluid from a hollow push rod acting against one end of the rocker arm.

United States Patent 1 [111 3,841,280

Lussier Oct. 15, 1974 VALVE ROCKER ARM AND PIVOT 3,099,983 I 8/1963 Orlando 123 9039 ASSEMBLY 3,139,872 7/1964 Thompson 123/9041 Inventor: Robert E. Lussier, Clarkston, Mich.

General Motors Corporation, Detroit, Mich.

Filed: Aug. 16, 1973 Appl. No.: 388,765

Assignee:

US. Cl 123/9039, 123/9042, 123/9047, 123/195 C Int. Cl. F011 1/18, F011 l/20 Field of Search 123/9039, 90.41, 90.42, 123/9047, 195 C References Cited UNITED STATES PATENTS Edwards Taylor Primary ExaminerManuel A. Antonakas Assistant ExaminerDanie1 J OConnor Attorney, Agent, or Firm-Arthur N. Krein [57] ABSTRACT A valve rocker arm and pivot assembly for use in the overhead valve gear of an internal combustion engine in which the valve rocker arm has a convex upper intermediate bearing portion fulcrumed against a concave bearing channel in the domed roof of a rocker arm cover fixed to the cylinder head of the engine. The bearing portion of the rocker arm is provided with an oil groove connected through a passage in the rocker arm to receive lubricating fluid from a hollow push rod acting against one end of the rocker arm.

6 Claims, 4 Drawing Figures VALVE ROCKER ARM AND PIVOT ASSEMBLY This invention relates to a valve rocker arm and pivot assembly and, in particular, to a valve rocker arm and pivot assembly for use as part of the overhead valve gear of an internal combustion engine.

In overhead type valve operating mechanisms, as used on an in-head internal combustion engine, various forms of valve rocker arms and supports therefor have been used whereby the valve rocker arm can transmit rec'iprocatory movement between a poppet valve and its push rod. In one form of such mechanism, the valve rocker arm is provided with an aperture intermediate its ends so that it can be positioned on a rocker arm shaft and pivoted thereabout. In another form, the rocker arm is provided intermediate its end with a spherical or U-shaped dished upper surface to receive a ball or U-shaped rocker fulcrum, respectively, fixed to a support, such as a stud, secured to the cylinder head of the engine. With the above described type of rocker arm and support structures, suitable arrangements were provided for lubrication of the rocker arm, as for example, with the aid of various forms of baffles and guides associated, for example, with the rocker cover of the engine to direct the oil to the pivotal elements of the rocker arm and fulcrum, as needed. Each of these prior art valve rocker arm and pivot arrangements required the use of extra parts or extensive machine operations to effect the desired result.

It is therefore a primary object of this invention to provide a valve rocker arm and pivot assembly whereby mounting of the rocker arms for pivotal movement is effected directly in the rocker arm cover, which was formerly used only to enclose the valve operating mechanism of the internal combustion engine.

Another object of this invention is to improve valve rocker arms whereby mounting of the rocker arm for pivotal movement and the lubrication thereof is facilitated without the use of extra parts.

Another object of this invention is to improve a valve rocker arm and pivot assembly whereby the pivot arrangement for the valve rocker arms can be fabricated as a unitary structure of sheet metal for all of the rocker arms in a cylinder bank and as the rocker cover for the overhead valve operating mechanism used in an internal combustion engine.

These and other objects of the invention are obtained by means of a valve rocker arm having surfaces on one side and adjacent to the ends thereof adapted to engage the driving and driven ends of a push rod and poppet valve, respectively, and an oppositely presenting convex shaped pivotal bearing surface on its opposite side intermediate the ends thereof which is adapted to be fulcrumed against a complementary shaped bearing channel formed in the rocker arm cover plate fixed to the cylinder head of an internal combustion engine. The convex bearing surface of the rocker arm is provided with an oil groove connected through a passage in the driving end of the rocker arm to the aperture of the hollow push rod acting at one end against the driving end of the rocker arm and at its other end against a hydraulic valve tappet engaging the cam on the camshaft of the engine.

For a better understanding of the invention as well as other objects and further features thereof, reference is had to the following detailed description of the invention to be read in connection with the accompanying drawings, wherein:

FIG. 1 is a cross sectional view of a portion of an internal combustion engine incorporating a valve rocker arm and pivot assembly in accordance with the invention;

FIG. 2 is a side view taken along lines 22 of FIG. 1 of the valve operating mechanism of the engine of FIG. 1 with parts broken away to show the details of its construction;

FIG. 3 is a top view taken along line 33 of FIG. 1 with the parts broken away to show details of the various elements; and,

FIG. 4 is a perspective view of a rocker arm in its locater strip used to effect assembly of the subject valve operating mechanism.

Referring now to the drawings, there is shown in FIG. 1 a portion of an internal combustion engine, of conventional overhead valve type, the engine including a cylinder block 10, having a number of cylinders 10a therein, and a cylinder head 11. The head 11 is provided with suitable inlet and exhaust ports for each cylinder, which ports are closed by valves, such as poppet valve 14. Slidably guided for axial reciprocation in the valve guide bore 12 of the cylinder head is the stem 13 of the poppet valve 14, the upper end portion of which projects above the cylinder head. In a conventional manner, the valve 14 is normally maintained in a closed position by a spring 15 encircling the upper portion of the stem 13 with one end of the spring engaging cylinder head 1 l and the other end engaging a conventional spring retainer collar 16 held on the stem 13 of the poppet valve by the flanged retainer 17 and keepers 18.

Similarly, extending through the bore 20 of the cylinder head is a hollow push rod 21 which is disposed laterally of the valve stem 13 of the poppet valve with which it cooperates, and has its upper end also projecting above the cylinder head. The lower end of the push rod 21 abuts the upper end of a hydraulic valve tappet 22 which is slidably guided for axial reciprocation in the bore 23 provided in the cylinder block 10. Suitably journaled in the cylinder block is a camshaft 24 carrying a cam25 which operatively engages the valve tappet 22 to cause it to reciprocate as determined by the profile of the cam 25. As is well known, the hydraulic valve tappet 22 is provided with a lubricating fluid, such as oil, from the oil passage 26 in the cylinder block 10.

Operatively connecting the push rod to the valve stem of the poppet valve, with which it cooperates, is a valve rocker arm, generally designated 30, constructed in accordance with the invention, pivotally fulcrumed in and supported by a valve rocker arm cover, generally designated 50, also constructed in accordance with the invention.

The valve rocker arm 30, made of a suitable material, preferably aluminum, includes a work arm 31 and a power arm 32 formed integral with and on opposite ends of the body 33 portion of the rocker arm. Preferably, the work arm 31 is apertured to receive the stem portion of an insert 34 which is in contact with the end of the valve stem while the power arm 32 is apertured on its under side to receive a bearing seat 35 with a concave, spherical socket therein which cooperates with the spherical upper end of push rod 21. The power arm 32, and work arm 31 can be considered as the driving end and driven end, respectively, of the rocker arm 30.

Body 33 of the rocker arm has an upper smooth bearing surface 36 and depending parallel side surfaces 37 with chamfered portions 38 therebetween, the bearing surface 36, in the longitudinal direction of the rocker arm, has an arcuate, convex shape of a predetermined radius. This bearing surface 36 is also provided with an oil groove 40 extending longitudinally thereof, which through an interconnecting passage 41 extending through the power arm 32 is in fluid communication with a passage 35a in bearing seat 35 to receive a lubricating fluid delivered through the aperture 21a in the upper spherical end of push rod 21.

The rocker arm 30 is also provided with a web 42 depending from the underside of the body 33 and extending longitudinally across the body from work arm 31 to power arm 32, for a purpose to be described.

Rocker cover 50, of general inverted, dish shaped configuration and formed, for example, of sheet steel has a flanged mounting portion 51 extending around the perimeter of the domed cover or roof portion 52 of this cover element, whereby the rocker cover can be secured as by threaded fasteners 53 to the top of the cylinder head 11, this rocker cover extending approximately the full length of the cylinder head as is well known in the art.

In accordance with the invention, the cover or roof portion 52 of the rocker cover, which is dome shaped in cross section, as seen in FIG. 1, is formed with spaced apart, inverted U-shaped bearing pockets 54 each such pocket being adapted to slidably and pivotably receive a rocker arm 30. The number and spacing of such pockets would correspond to the number and spacing of the rocker arms used to effect operation of the poppet valves in the cylinder bank of the engine. Each bearing pocket 54, formed complementary to the rocker arm 30 to be fulcrumed therein, includes spaced apart parallel depending sides 55 to slidably receive the side surfaces 37 of the rocker arm and an interconnecting upper bearing member 56 having an inner bearing surface inside the cover against which the bearing surface 36 of the rocker arm 30 slidably abuts, the bearing member 56 having a concave shape, of a predetermined radius, extending in a direction between the push rod 21 and poppet valve 14.

During engine operation, the interface between the bearing surface 36 of rocker arm 30 and the bearing member 56 is pressure lubricated by lubricating fluid delivered into the oil groove 40 of the rocker arm. As best seen in FIG. 1, this lubricating fluid is delivered to the rocker arm by means of the push rod 21, which is of hollow tubular construction and is provided with an aperture 210 at its upper spherical end which communicates with the interior of the push rod. The hollow push rod 21 is provided with pressurized lubricant, such as oil, by means of the hydraulic tappet 22 from oil passage 26 in a manner well known in the art, to provide for the lubrication of the rocker arm 30 in the bearing pocket 54 of rocker arm cover 50. The manner of supplying oil under pressure to the push rod 21 is conventional and forms no part of the present invention and, therefore, no further description is deemed necessary with respect thereto.

A rocker arm locater, generally designated 60, although not forming a functional part of the assembled valve train, is provided to facilitate assembly of the push rods 21, rocker arms 30 and rocker arm cover 50, this rocker arm locater being of necessity left in place after assembly of the valve train as seen in FIGS. 1 and 2.

The rocker arm locater 60 is preferably a single piece drop-in support, indexed to the cylinder head 11 machining and is adapted to support and align all of the rocker arms 30 and to guide all of the push rods 21 in one cylinder bank of the engine so that the rocker arm cover can be positioned over the rocker arms with the rocker arms 30 aligned with the bearing pockets 54 in the rocker arm cover 50 after which the rocker arm cover can then be firmly drawn down tight against the cylinder head to the position shown in FIG. 1 and secured thereto by the fasteners 53.

In the embodiment shown, the rocker arm locater 60, made of a suitable material, includes an elongated strip 61 of a length less than the length of the rocker arm cover 50 and adapted, as hereinafter described, to be positioned longitudinally with respect to the cylinder head 11, the strip 61 supporting a plurality of spaced apart laterally positioned, upstanding, resilient U- shaped clips 62, the number of such clips corresponding to the number of rocker arms used in the cylinder bank of the engine. Each clip 62, as seen in FIG. 2, is adapted to slidably support a rocker arm 30 by engagement of the web 42 of the rocker arm between the legs of the clip, the rocker arm thus being held in alignment over the valve stem 13 of a push rod and over a push rod 21, with the valve stem engaging the insert 34 and the spherical end of the push rod 21 seated in the bearing seat 35 of the rocker arm.

The rocker arm locater is also provided with push rod guides 63, each having an aperture 64 therethrough to slidably receive and position a push rod 21 relative to the bearing seat of a rocker arm, each guide 63 extending laterally from one side of the strip 61 in alignment with the clip 62 with which it cooperates.

Rocker arm locater 60 is secured to the top of the cylinder head 11 by means of one or more pedestal bases 65 depending from the strip 61, each such pedestal base 65 having a reduced plug 66 portion at its lower free end which is adapted to be inserted into a suitable apertured boss 11a provided for this purpose on the cylinder head 11, whereby the shoulder portion 65a of a pedestal base rests against the top of the boss 1 1a and the clips 62 are positioned at the desired height to support the rocker arms 30 for assembly of the rocker arm cover.

It is apparent that with the use of the subject valve rocker arm and pivot assembly arrangement disclosed, conventional rocker arm studs, rocker arm balls, rocker arm ball retaining nuts, push rod guides, guide retainer screws and/or rocker arm shafts are all eliminated. In addition, the necessity for all of the cylinder head rocker arm stud boss material and the machining thereof will be eliminated. Instead, with the subject arrangement, the rocker arm cover, that would normally only serve its conventional function, is now modified to act as a support guide and fulcrum for the rocker arms.

What is claimed is:

1. A rocker arm and pivot assembly for an internal combustion engine having a cylinder block with at least one cylinder therein and a head closing the cylinder, a poppet valve in the head and having a valve stem extending above the head and, a hollow push rod having an apertured spherical end extending above the head, said rocker arm and pivot including a rocker arm cover secured to the cylinder head and having a domed wall extending over the poppet valve and push rod in spaced relation thereto, said domed wall of said rocker arm cover having an inverted U-shaped bearing pocket with an upper bearing surface curved in an arc of predetermined radius and extending between the poppet valve and the push rod, and a rocker arm extending between and engaged at a driving end with the push rod and at a power end with the valve stem of the poppet valve, said rocker arm having a curved intermediate upper bearing portion between said driving end and said driven end with an upper bearing surface and opposed side bearing surfaces formed complementary to said bearing pocket in said rocker arm cover, said rocker arm being slidably and pivotally received in said bearing pocket for pivotal movement in the vertical plane extending between the poppet valve and the push rod while engaged therewith so that reciprocable movement of the push rod is translated to the poppet valve.

2. A rocker arm and pivot assembly according to claim 1 wherein said rocker arm at its said driving end is provided with an apertured socket to receive the upper end of the push rod in oil discharge relationship therefrom and wherein its said upper bearing surface has an oil groove extending longitudinally thereof, said rocker arm further having an oil passage therein extending from said oil groove to said apertured socket.

3. A rocker arm and pivot assembly according to claim 2 wherein said rocker arm further includes a web integral with and depending from said intermediate bearing portion between said driving end and said driven end, said rocker arm and pivot assembly further including a rocker arm locater means supported by and indexed to the head, said rocker arm locater means including an upstanding, resilient U-shaped support clip to slidably receive said web of said rocker arm to support said rocker arm above and in alignment with the poppet valve and push rod and, an apertured push rod guide in alignment with said clip to slidably receive the push rod.

4. A valve operating assembly for use in an overhead valve in-head engine, said valve operating assembly including an upwardly extending, reciprocable, hollow push rod, a poppet valve with an operating stem having an upwardly exposed end, a rocker arm extending between said push rod and said stem, means at one end on the underside of said rocker arm for operatively receiving said push rod to rock said rocker arm, means at the opposite end of said rocker arm on the underside thereof for operatively receiving said stem of said poppet valve whereby reciprocable movement of said push rod is translated to said poppet valve, said rocker arm intermediate said ends having an upper bearing surface and side bearing surfaces extending between said ends of said rocker arm, said upper bearing surface extending in an arcuate path, of predetermined radius, between said ends and, a rocker arm cover fixed to the head of said engine, said rocker arm cover having a dome shaped roof with an inverted U-shaped bearing pocket therein to slidably receive said rocker arm, the portion of said inverted U-shaped pocket engaging said upper bearing surface of said rocker arm being formed complementary to the arcuate path of said upper bearing surface of said rocker arm, said rocker arm being thus fulcrumed in said bearing pocket for pivotal movement in a vertical plane extending between said poppet valve and said push rod.

5. A valve operating assembly according to claim 4 wherein said means at one end of said rocker arm for operatively receiving said push rod is an apertured socket to receive an end of said push rod in oil discharge relationship therefrom and wherein said upper bearing surface of said rocker arm has an oil groove extending longitudinally thereof and, an oil passage in said rocker arm extending in fluid flow relation from said oil groove to said apertured socket.

6. A rocker arm and pivot assembly for use in the overhead valve gear mechanism of an internal combustion engine, the rocker arm of said assembly being used to transmit motion between a hollow push rod and a laterally separated poppet valve both extending upward from the cylinder head of the engine, with the push rod having an aperture at its upper end in communication with a source of pressurized lubricant in the hollow interior of the push rod, said rocker arm and pivot assembly including a rocker arm cover having a dome-shaped wall with a mounting flange around the periphery of the dome shaped wall adapted to be releasably secured to the cylinder head of the engine with the dome shaped wall of the rocker arm cover positioned over and in spaced relation to the poppet valve and push rod, an inverted U-shaped bearing pocket in said domed wall, the inner upper wall surface of said bearing pocket extending in an arcuate path of predetermined radius between and above the push rod and poppet valve, said rocker arm and pivot assembly further including a rocker arm extending between said push rod and said stem and including an apertured driving end socketably engaged with the upper end of the push rod in oil discharge relationship therefrom and a driven end engaged against the poppet valve and an intermediate portion therebetween having an upper bearing surface and side bearing surfaces of a shape and size complementary to said bearing pocket in said rocker arm cover, said bearing surfaces of said rocker arm being slidably and pivotably received in said bearing pocket for movement in a vertical plane extending between the poppet valve and the push rod, said upper bearing surface having an oil groove extending longitudinally thereof in fluid flow relationship to said apertured driving end of said rocker arm. 

1. A rocker arm and pivot assembly for an internal combustion engine having a cylinder block with at least one cylinder therein and a head closing the cylinder, a poppet valve in the head and having a valve stem extending above the head and, a hollow push rod having an apertured spherical end extending above the head, said rocker arm and pivot including a rocker arm cover secured to the cylinder head and having a domed wall extending over the poppet valve and push rod in spaced relation thereto, said domed wall of said rocker arm cover having an inverted U-shaped bearing pocket with an upper bearing surface curved in an arc of predetermined radius and extending between the poppet valve and the push rod, and a rocker arm extending between and engaged at a driving end with the push rod and at a power end with the valve stem of the poppet valve, said rocker arm having a curved intermediate upper bearing portion between said driving end and said driven end with an upper bearing surface and opposed side bearing surfaces formed complementary to said bearing pocket in said rocker arm cover, said rocker arm being slidably and pivotally received in said bearing pocket for pivotal movement in the vertical plane extending between the poppet valve and the push rod while engaged therewith so that reciprocable movement of the push rod is translated to the poppet valve.
 2. A rocker arm and pivot assembly according to claim 1 wherein said rocker arm at its said driving end is provided with an apertured socket to receive the upper end of the push rod in oil discharge relationship therefrom and wherein its said upper bearing suRface has an oil groove extending longitudinally thereof, said rocker arm further having an oil passage therein extending from said oil groove to said apertured socket.
 3. A rocker arm and pivot assembly according to claim 2 wherein said rocker arm further includes a web integral with and depending from said intermediate bearing portion between said driving end and said driven end, said rocker arm and pivot assembly further including a rocker arm locater means supported by and indexed to the head, said rocker arm locater means including an upstanding, resilient U-shaped support clip to slidably receive said web of said rocker arm to support said rocker arm above and in alignment with the poppet valve and push rod and, an apertured push rod guide in alignment with said clip to slidably receive the push rod.
 4. A valve operating assembly for use in an overhead valve in-head engine, said valve operating assembly including an upwardly extending, reciprocable, hollow push rod, a poppet valve with an operating stem having an upwardly exposed end, a rocker arm extending between said push rod and said stem, means at one end on the underside of said rocker arm for operatively receiving said push rod to rock said rocker arm, means at the opposite end of said rocker arm on the underside thereof for operatively receiving said stem of said poppet valve whereby reciprocable movement of said push rod is translated to said poppet valve, said rocker arm intermediate said ends having an upper bearing surface and side bearing surfaces extending between said ends of said rocker arm, said upper bearing surface extending in an arcuate path, of predetermined radius, between said ends and, a rocker arm cover fixed to the head of said engine, said rocker arm cover having a dome shaped roof with an inverted U-shaped bearing pocket therein to slidably receive said rocker arm, the portion of said inverted U-shaped pocket engaging said upper bearing surface of said rocker arm being formed complementary to the arcuate path of said upper bearing surface of said rocker arm, said rocker arm being thus fulcrumed in said bearing pocket for pivotal movement in a vertical plane extending between said poppet valve and said push rod.
 5. A valve operating assembly according to claim 4 wherein said means at one end of said rocker arm for operatively receiving said push rod is an apertured socket to receive an end of said push rod in oil discharge relationship therefrom and wherein said upper bearing surface of said rocker arm has an oil groove extending longitudinally thereof and, an oil passage in said rocker arm extending in fluid flow relation from said oil groove to said apertured socket.
 6. A rocker arm and pivot assembly for use in the overhead valve gear mechanism of an internal combustion engine, the rocker arm of said assembly being used to transmit motion between a hollow push rod and a laterally separated poppet valve both extending upward from the cylinder head of the engine, with the push rod having an aperture at its upper end in communication with a source of pressurized lubricant in the hollow interior of the push rod, said rocker arm and pivot assembly including a rocker arm cover having a dome-shaped wall with a mounting flange around the periphery of the dome shaped wall adapted to be releasably secured to the cylinder head of the engine with the dome shaped wall of the rocker arm cover positioned over and in spaced relation to the poppet valve and push rod, an inverted U-shaped bearing pocket in said domed wall, the inner upper wall surface of said bearing pocket extending in an arcuate path of predetermined radius between and above the push rod and poppet valve, said rocker arm and pivot assembly further including a rocker arm extending between said push rod and said stem and including an apertured driving end socketably engaged with the upper end of the push rod in oil discharge relationship therefrom and a driven end engaged against the poppet valve and an intermediate porTion therebetween having an upper bearing surface and side bearing surfaces of a shape and size complementary to said bearing pocket in said rocker arm cover, said bearing surfaces of said rocker arm being slidably and pivotably received in said bearing pocket for movement in a vertical plane extending between the poppet valve and the push rod, said upper bearing surface having an oil groove extending longitudinally thereof in fluid flow relationship to said apertured driving end of said rocker arm. 